1. Field of the Invention
The present invention relates to socket type contacts for use with an insulative housing which solders to a printed circuit board and can accept a pin grid array (PGA) having a plurality of pins.
2. Description of the Prior Art
The contacts used in the PGA socket housing includes two types of which one is of a single tubular socket integrally having a plurality of punched-out or sheared-off independent fingers (generally three) extending inwardly to electrically and mechanically engage a corresponding pin received therein for connection, for example, U.S. Pat. Nos. 4,934,967 and 4,707,052. The other type has a tubular socket incorporating therein a separate clip or insert having a ring portion at the top to locate and hold the clip within the socket, and having a plurality of cantilever beams extending downwardly therefrom and converging toward each other for engagement with an inserted corresponding pin by their distal free ends, for example, U.S. Pat. Nos. 4,186,990, 4,236,776, 4,296,993, 4,415,212, 4,470,649, 4,534,603, 4,784,662, 4,822,288 and 4,981,450.
Regardless of either type, a disadvantage of the prior art contacts is that each finger or cantilever beam is separated from each other so when a lead pin from a PGA package is inserted into the socket contact of either type, the amount of deflection for each leg will vary greatly, depending on the angle and position of entry. Some legs may even individually experience a torsional twist, rather than a linear deflection because of the off-center entry of the lead pin. Consequently, the insertion force, which is a function of the normal force exerted on the PGA lead pins, which is a function of the amount and type of deflection of each finger or cantilever beam, will be higher then a more forgiving design. Accordingly, one solution for this problem is to properly combine the free ends of these cantilever beams together so the fingers are moved as a unit when the PGA lead pin is off-center due to angularity or position. Thus, the deflection of the cantilever beams is more uniform and linear than with the other designs. Therefore, the total insertion force of the PGA package into the insulative housing can be reduced with this design.